The present invention refers to a compact rolling mill for rolling structural steel through rolling stands arranged in several rolling lines. In addition, the present invention refers to a method for rolling structural steel in such rolling mills.
Compact rolling mills of this type include universal rolling stands and two-high rolling stands with conveyors for longitudinally transporting a rolling stock in a rolling line and conveyors for transporting the rolling stock between rolling lines, as well as guiding devices for the rolling stock during its travel between the stands. In contrast to large and expensive shape mill trains which have a great demand on space, especially in longitudinal extension, and allow the rolling of only one profile so as to be usable in an economic manner only when rolling at high production, compact rolling mills are applicable for a wide range of section rolling, including beams, rails and sheet piles, and can be run in an economic manner also at smaller production quantities.
Known rolling mills of this type which only include universal stands and possibly two-high edging stands incur, however, high expenses and operating costs when covering a wide program so that a high output of beams or rail is required to render the operation economical.
It has been proposed to use a combination of universal stands and two-high stands for rolling the profile program which lead to a limited, yet not sufficient increase of available grooves but resulted also in increased barrel lengths of the two-high rolls, wider roller tracks and larger cross conveyors. In addition, the substantial length of roll barrels lead to sagging of the rolls and thus impaired stiffness of the stands. To counter this drawback, rolling stands with variable distance of the roll support i.e. shiftable rolling stands have been proposed. This, however, also lead to high expenditures and high operating costs when changing the unit.
The use of additional two-high rolling stands for broadening the production program incurred also high investments and a considerably increased demand on space so that the production of at least some sections must be increased to render the overall program economical.